Encrypted storage devices are used to store sensitive and confidential information. Drives of the self-encrypting variety contain their own encryption engine in which data gets encrypted when being written, and decrypted when read. Paramount to this whole process is the encryption key. How did this key get created? Who created it and in what country? What is its entropy?
A strong encryption key has the maximum amount of entropy allowed by its size. For example, a 256 bit AES key should have 256 bits of entropy. An encryption key based on a user password has relatively little entropy. A password of 8 characters, assuming upper and lower case letters and numbers, can generate up to 218,340,105,584,896 different numbers, which seems like a lot, but not when compared to 1.16×1077 possible values available from a 256 bit key.
Given the ever increasing processing power of computers, it is desirable to have maximum entropy in order to thwart brute force attacks. Therefore, an encryption key based on a user password is not the most desired means.
Generating a truly random number is difficult. Some mass storage manufacturers program encryption keys at the factory. These keys are generated by factory computers and copied into a region of private memory within the mass storage device. Customers are typically concerned with how these keys are created and whether the factory can associate a serial number with an encryption key. In addition, can the factory be trusted to create encryption keys with sufficient entropy? And, do mass storage devices contain duplicate keys?
Given the difficulty of having a mass storage device create its own entropy, once factory programmed encryption keys are zeroized, the drive will no longer work and becomes a paper weight.
There is accordingly an unmet need in the art to provide a mass storage device with the built-in ability to create a virtually unlimited supply of encryption keys with the entropy equivalent to its key length.
An example of a prior art device is shown in US Publication No. 2011/0075840, entitled Method and System for Generating Random Numbers in a Storage Device, filed Sep. 30, 2009, to Fernando Zayas et al.
Another example of a prior art device is shown in US Publication No. 2008/0263363, entitled Portable Data Encryption Device with Configurable Security Functionality and Method for File Encryption, filed Jan. 22, 2008 to Robert R. Jueneman.
A further example of such a prior art device is shown in U.S. Pat. No. 6,044,388, entitled Pseudo-random number generator, issued Mar. 28, 2000 to Robert S. Debellis et al.
Another prior art device is shown in U.S. Pat. No. 5,778,069, entitled Non-biased pseudo random number generator, issued Jul. 7, 1998 to Thomlinson et al.
A prior art device is shown in U.S. Pat. No. 8,001,054, issued Aug. 16, 2011 entitled System and method for generating an unpredictable number using a seeded algorithm, to Lee J. Peart et al.
A further prior art device is shown in U.S. Pat. No. 4,694,412, issued Sep. 15, 1987, entitled Random number generator for use in an authenticated read-only memory, to Domenik et al.
A prior art device is shown in U.S. Pat. No. 7,421,462, issued Sep. 2, 2008, entitled Method and apparatus for generating a random bit stream, to Castejon-Amenedo et al.
Another prior art device is shown in U.S. Pat. No. 6,728,740, entitled Random number generator seeding method and apparatus, to Kelly et al. This patent shows a plurality of event sensors associated with separate counters, and which is used to create a seed number which is then stored in a seed register. The counters identified in this patent are for a time stamp count, instructions executed, date of reads and writes, and a microsecond timer.
A publication in US 2012/0179735 having a filing date of Jan. 16, 2011 shows a device entitled Scalable random number generation, having inventors Ferguson et al.